This invention relates to a vehicle electric brake system having stationary vehicle holding brake torque control.
Vehicles which rely on electrical power to generate a braking force are required to continuously apply a holding torque when the vehicle is stationary. Without an estimate of the condition of the vehicle, a braking force equal to the maximum rated vehicle weight (GVW) times the sine of a maximum incline must be maintained in order to assure the vehicle is maintained stationary for any load and incline condition. This results in applying a greater braking torque than is necessary under most conditions.
Since braking torque in electric braking systems is proportional to current in the braking actuators (such as electric motor actuators), unnecessary current will be applied to the actuators under most conditions when the vehicle is stopped. This places an unnecessary strain on the vehicle's electrical system and generates excessive heat in the actuators and the electronic brake controller.